Nowadays, different types of complex production wells are applied in challenging reservoirs in order to maximize oil recovery. A representative application is the fishbone multilateral horizontal wells, which have advantages of expanding the drainage area information and reducing the pressure loss in the long single lateral wellbore. This paper investigated the performance of fishbone wells and derived a wellbore and reservoir flow coupling model for fishbone multilateral wells in the bottom water reservoirs. The new model considered plenty of parameters that may have significant impacts on productivity and pressure drop in the well, including the fishbone structure, the main and branch wellbores’ length, the spacing distance of the branch wellbores, wellbore radius, and preformation parameters. Furthermore, a sensitivity analysis example by the numerical method is presented in this paper. Compared with other models, our coupling model, when it is degraded to horizontal well, is more consistent with the results of actual field situation. In another comparative analysis, the results of the new model with branches show a good match with the numerical simulation results by software. The proposed method in this paper can be used as a valuable tool to analyze the productivity, wellbore inflow profile, and pressure profile of the fishbone multilateral wells in the bottom water reservoir.